High-frequency circuits are often manufactured on printed circuit assemblies (“PCAs”). High-frequency launch connectors are used to bring high frequency signals, such as radio frequency (“RF”) signals and microwave signals, on and off the PCA. High-frequency launch connectors have a coaxial connector interface on one end, and connect to the PCA on the other end. A variety of types of coaxial connector standards are known and in widespread use, such as SMA, SMB, SMC, SSMA, 3.5-mm, 2.4-mm, and 1.85-mm standards. Coaxial cables with a mating coaxial interface are connected to the coaxial connector interface of the high-frequency launch connector on the PCA. Generally, each of the various coaxial connector types is available in a variety of styles that are adapted for various applications.
Some high-frequency launch connectors are designed to be assembled onto a PCA using surface mount technology (“SMT”). One SMT edge launch connector has a female-type SMA coaxial connector interface on one end and a center pin extending from the other end. The center pin is typically captivated in a dielectric material, such as TEFLON™, and forms a coaxial transmission structure having a characteristic impedance with the metal body of the SMT edge launch connector. Ledges extend away from the metal body to support the SMT edge launch connector in a cutout in a printed circuit board (“PCB”) during assembly (soldering).
The center pin of the SMT edge launch connector is soldered to the center conductor of an impedance-controlled structure on the PCA. The impedance-controlled structure is typically designed to have the same characteristic impedance as the coaxial transmission structure of the SMT edge launch connector. However, a small gap often exists between the end of the center conductor on the PCB and the end of the metal body of the SMT edge launch connector. This gap forms an impedance discontinuity between the coaxial transmission structure and the impedance-controlled structure on the PCB, which degrades high-frequency performance. Similarly, the center pin can radiate and/or receive unwanted high-frequency signals. Adding shielding structures and/or tuning structures to the PCA after soldering the SMT edge launch connector adds additional cost and manufacturing time.
Also, the dielectric material in the coaxial transmission structure in the SMT edge launch connector often expands when the SMT edge launch connector is soldered to the PCB and pushes the edge launch connector away from the edge of the PCB. This creates a gap between the body of the edge launch connector and the edge of the PCA, which can further degrade high-frequency performance.
Therefore, it is desirable to provide an edge launch connector with improved impedance continuity and less susceptibility to radiating and/or receiving unwanted high-frequency signals.